Butt plate retention mechanism for an ammunition magazine
A magazine for feeding ammunition to a firearm includes a tube surrounding a longitudinal axis and defining a central space for receiving the ammunition. The tube has first and second ends. A follower is slidably movable within the tube. A butt plate is removeably attached to the first end. The butt plate defines a bore. A plunger is movably positioned within the bore and includes a first mounting cam. A first catch, mounted on the butt plate, is engageable with the tube proximate to the first end. The first catch is movable relative to the butt plate in a direction transverse to the longitudinal axis. The first catch includes a cam follower engageable with the first cam. A spring acts between the plunger and the follower for biasing the plunger toward the butt plate and the follower toward the second end.
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This application is based upon and claims benefit of priority to U.S. Provisional application No. 62/932,695, filed Nov. 8, 2019, which application is hereby incorporated by reference herein.
FIELD OF THE INVENTIONThis invention relates to ammunition magazines for semiautomatic firearms.
BACKGROUNDCertain legal jurisdictions place limits on the capacity of magazines for semiautomatic firearms. As these jurisdictions are relatively few in number, and thus will generate a relatively small sales volume of reduced capacity magazines, it is advantageous to develop a reduced capacity magazine design which can be manufactured without the need for special tooling and the associated capital investment and expense over and above the expense and tooling needed for the manufacture of standard capacity magazines having a capacity determined by the design of the firearm and not by legislation.
SUMMARYThis invention concerns a magazine for feeding ammunition to a firearm. In an example embodiment, the magazine comprises a tube surrounding a longitudinal axis and defining a central space for receiving the ammunition. The tube has first and second ends oppositely disposed. A follower is slidably movable within the tube along the longitudinal axis. A butt plate is removeably attached to the first end of the tube. The butt plate defines a bore extending therethrough. A plunger is movably positioned within the bore of the butt plate. The plunger comprises a first cam mounted thereon. A first catch is mounted on the butt plate and is engageable with the tube proximate to the first end thereof. The first catch is movable relatively to the butt plate in a direction transverse to the longitudinal axis. The first catch comprises a first cam follower engageable with the first cam. A spring acts between the plunger and the follower for biasing the plunger toward the butt plate and the follower toward the second end of the tube. The first cam acts on the first cam follower to position the first catch into engagement with the tube upon motion of the plunger toward the butt plate, thereby retaining the butt plate to the tube. The first cam acts on the first cam follower to position the first catch out of engagement with the tube, thereby releasing the butt plate from the tube upon motion of the plunger toward the follower.
As an example, the bore is oriented parallel to the longitudinal axis of the tube.
In an example, the magazine further comprises a first slot located within the tube proximate to the first end thereof. The first catch comprises a first shoulder projecting transversely to the longitudinal axis. The first shoulder is engageable within the first slot upon the motion of the plunger toward the butt plate.
As an example, the first cam comprises a first trunnion projecting from the plunger. The first cam follower comprises a first track positioned within the first catch. The first cam is received within the first track.
In an example, the magazine further comprises a piston positioned within the tube between the spring and the butt plate. The piston is engageable with the plunger for transmitting a biasing force from the spring thereto. In a particular example, the piston comprises a panel and a boss. The panel is movable along the longitudinal axis within the tube. The boss projects from the panel into the bore for engagement with the plunger.
As an example, the butt plate comprises a lowermost surface. The longitudinal axis of the tube is oriented at an angle to the lowermost surface.
In an example, the magazine further comprises a second cam mounted on the plunger. A second catch is mounted on the butt plate and engageable with the tube proximate to the first end thereof. The second catch is movable relatively to the butt plate in a direction transverse to the longitudinal axis. The second catch comprises a second cam follower engageable with the second cam. The second cam acts on the second cam follower to position the second catch into engagement with the tube upon motion of the plunger toward the butt plate, thereby retaining the butt plate to the tube. The second cam acts on the second cam follower to position the second catch out of engagement with the tube, thereby releasing the butt plate from the tube upon motion of the plunger toward the follower. In a particular example, the second cam is mounted on an opposite side of the plunger from the first cam. In another particular example, the second catch is mounted on an opposite side of the plunger from the first catch.
As an example, the magazine further comprises a second slot located within the tube proximate to the first end thereof. The second catch comprises a second shoulder projecting transversely to the longitudinal axis. The second shoulder is engageable within the second slot upon the motion of the plunger toward the butt plate.
In an example, the second cam comprises a second trunnion projecting from the plunger. The second cam follower comprises a second track positioned within the second catch. The second cam is received within the second track.
This invention further concerns a magazine for feeding ammunition to a firearm. The magazine comprises a tube surrounding a longitudinal axis and defining a central space for receiving the ammunition. The tube has first and second ends oppositely disposed. A follower is slidably movable within the tube along the longitudinal axis. A butt plate is removeably attached to the first end of the tube. The butt plate defines a bore extending therethrough. A plunger is movably positioned within the bore of the butt plate. The plunger comprises a first cam mounted thereon. First and second catches are mounted on the butt plate and engageable with the tube proximate to the first end thereof. The first and second catches are movable relatively to the butt plate in opposite directions to one another transverse to the longitudinal axis. The first catch comprises a first cam follower engageable with the first cam and the second catch comprises a second cam follower engageable with the second cam. A spring acts between the plunger and the follower for biasing the plunger toward the butt plate and the follower toward the second end of the tube. The first and second cams act on the first and second cam followers respectively to position the first and second catches into engagement with the tube upon motion of the plunger toward the butt plate, thereby retaining the butt plate to the tube. The first and second cams act on the first and second cam followers respectively to position the first and second catches out of engagement with the tube, thereby releasing the butt plate from the tube upon motion of the plunger toward the follower.
In an example, wherein the bore is oriented parallel to the longitudinal axis of the tube.
As an example, the magazine further comprises first and second slots located within the tube proximate to the first end thereof. The first catch comprises a first shoulder projecting transversely to the longitudinal axis and the second catch comprises a second shoulder projecting transversely to the longitudinal axis. The first and second shoulders are respectively engageable within the first and second slots upon the motion of the plunger toward the butt plate.
In an example, the first cam comprises a first trunnion projecting from the plunger. The first cam follower comprises a first track positioned within the first catch. The first cam is received within the first track. The second cam comprises a second trunnion projecting from the plunger. The second cam follower comprises a second track positioned within the second catch. The second cam is received within the second track.
As an example, the magazine further comprises a piston positioned within the tube between the spring and the butt plate. The piston is engageable with the plunger for transmitting a biasing force from the spring thereto. In a particular example, the piston comprises a panel and a boss. The panel is movable along the longitudinal axis within the tube. The boss projects from the panel into the bore for engagement with the plunger.
In an example, the butt plate comprises a lowermost surface. The longitudinal axis of the tube is oriented at an angle to the lowermost surface. As an example, the second cam is mounted on an opposite side of the plunger from the first cam. In an example, the second catch is mounted on an opposite side of the plunger from the first catch.
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The magazine 10 with the butt plate retention mechanism described herein is expected to provide a reduced capacity magazine design which can be manufactured without the need for special tooling and the associated capital investment and expense over and above the expense and tooling needed for the manufacture of standard capacity magazines having a capacity determined by the design of the firearm.
Claims
1. A magazine for feeding ammunition to a firearm, said magazine comprising:
- a tube surrounding a longitudinal axis and defining a central space for receiving said ammunition, said tube having first and second ends oppositely disposed;
- a follower slidably movable within said tube along said longitudinal axis;
- a butt plate removeably attached to said first end of said tube, said butt plate defining a bore extending therethrough;
- a plunger movably positioned within said bore of said butt plate, said plunger comprising a first cam mounted thereon;
- a first catch mounted on said butt plate and engageable with said tube proximate to said first end thereof, said first catch being movable relatively to said butt plate in a direction transverse to said longitudinal axis, said first catch comprising a first cam follower engageable with said first cam;
- a spring acting between said plunger and said follower for biasing said plunger toward said butt plate and said follower toward said second end of said tube; wherein
- said first cam acts on said first cam follower to position said first catch into engagement with said tube upon motion of said plunger toward said butt plate, thereby retaining said butt plate to said tube, and, said first cam acts on said first cam follower to position said first catch out of engagement with said tube, thereby releasing said butt plate from said tube upon motion of said plunger toward said follower.
2. The magazine according to claim 1, wherein said bore is oriented parallel to said longitudinal axis of said tube.
3. The magazine according to claim 1, further comprising:
- a first slot located within said tube proximate to said first end thereof; and wherein
- said first catch comprises a first shoulder projecting transversely to said longitudinal axis, said first shoulder being engageable within said first slot upon said motion of said plunger toward said butt plate.
4. The magazine according to claim 1, wherein:
- said first cam comprises a first trunnion projecting from said plunger;
- said first cam follower comprises a first track positioned within said first catch, said first cam being received within said first track.
5. The magazine according to claim 1, further comprising a piston positioned within said tube between said spring and said butt plate, said piston being engageable with said plunger for transmitting a biasing force from said spring thereto.
6. The magazine according to claim 5, wherein said piston comprises:
- a panel movable along said longitudinal axis within said tube;
- a boss projecting from said panel into said bore for engagement with said plunger.
7. The magazine according to claim 1, wherein said butt plate comprises a lowermost surface, said longitudinal axis of said tube being oriented at an angle to said lowermost surface.
8. The magazine according to claim 1, further comprising:
- a second cam mounted on said plunger;
- a second catch mounted on said butt plate and engageable with said tube proximate to said first end thereof, said second catch being movable relatively to said butt plate in a direction transverse to said longitudinal axis, said second catch comprising a second cam follower engageable with said second cam; wherein
- said second cam acts on said second cam follower to position said second catch into engagement with said tube upon motion of said plunger toward said butt plate, thereby retaining said butt plate to said tube, said second cam acting on said second cam follower to position said second catch out of engagement with said tube, thereby releasing said butt plate from said tube upon motion of said plunger toward said follower.
9. The magazine according to claim 8, wherein said second cam is mounted on an opposite side of said plunger from said first cam.
10. The magazine according to claim 8, wherein said second catch is mounted on an opposite side of said plunger from said first catch.
11. The magazine according to claim 8, further comprising:
- a second slot located within said tube proximate to said first end thereof; and wherein
- said second catch comprises a second shoulder projecting transversely to said longitudinal axis, said second shoulder being engageable within said second slot upon said motion of said plunger toward said butt plate.
12. The magazine according to claim 8, wherein:
- said second cam comprises a second trunnion projecting from said plunger;
- said second cam follower comprises a second track positioned within said second catch, said second cam being received within said second track.
13. A magazine for feeding ammunition to a firearm, said magazine comprising:
- a tube surrounding a longitudinal axis and defining a central space for receiving said ammunition, said tube having first and second ends oppositely disposed;
- a follower slidably movable within said tube along said longitudinal axis;
- a butt plate removeably attached to said first end of said tube, said butt plate defining a bore extending therethrough;
- a plunger movably positioned within said bore of said butt plate, said plunger comprising a first cam mounted thereon;
- first and second catches mounted on said butt plate and engageable with said tube proximate to said first end thereof, said first and second catches being movable relatively to said butt plate in opposite directions to one another transverse to said longitudinal axis, said first catch comprising a first cam follower engageable with said first cam, said second catch comprising a second cam follower engageable with said second cam;
- a spring acting between said plunger and said follower for biasing said plunger toward said butt plate and said follower toward said second end of said tube; wherein
- said first and second cams act on said first and second cam followers respectively to position said first and second catches into engagement with said tube upon motion of said plunger toward said butt plate, thereby retaining said butt plate to said tube, and, said first and second cams act on said first and second cam followers respectively to position said first and second catches out of engagement with said tube, thereby releasing said butt plate from said tube upon motion of said plunger toward said follower.
14. The magazine according to claim 13, wherein said bore is oriented parallel to said longitudinal axis of said tube.
15. The magazine according to claim 14, further comprising:
- first and second slots located within said tube proximate to said first end thereof; and wherein
- said first catch comprises a first shoulder projecting transversely to said longitudinal axis, said second catch comprises a second shoulder projecting transversely to said longitudinal axis, said first and second shoulders being respectively engageable within said first and second slots upon said motion of said plunger toward said butt plate.
16. The magazine according to claim 14, wherein:
- said first cam comprises a first trunnion projecting from said plunger;
- said first cam follower comprises a first track positioned within said first catch, said first cam being received within said first track;
- said second cam comprises a second trunnion projecting from said plunger;
- said second cam follower comprises a second track positioned within said second catch, said second cam being received within said second track.
17. The magazine according to claim 13, further comprising a piston positioned within said tube between said spring and said butt plate, said piston being engageable with said plunger for transmitting a biasing force from said spring thereto.
18. The magazine according to claim 17, wherein said piston comprises:
- a panel movable along said longitudinal axis within said tube;
- a boss projecting from said panel into said bore for engagement with said plunger.
19. The magazine according to claim 13, wherein said butt plate comprises a lowermost surface, said longitudinal axis of said tube being oriented at an angle to said lowermost surface.
20. The magazine according to claim 13, wherein said second cam is mounted on an opposite side of said plunger from said first cam.
21. The magazine according to claim 13, wherein said second catch is mounted on an opposite side of said plunger from said first catch.
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Type: Grant
Filed: Nov 6, 2020
Date of Patent: Aug 24, 2021
Patent Publication Number: 20210140730
Assignee: Smith & Wesson, Inc. (Springfield, MA)
Inventor: Joseph DeJessa (West Brookfield, MA)
Primary Examiner: Reginald S Tillman, Jr.
Application Number: 17/091,120
International Classification: F41A 9/71 (20060101); F41A 9/70 (20060101);